1. Field of the Invention
The present invention is generally in the field of electronic circuits and systems. More specifically, the present invention is in the field of communications circuits and systems.
2. Background Art
Transceivers are typically used in communications systems to support transmission and reception of communications signals through a common antenna, for example, at radio frequency (RF) in a cellular telephone or other mobile communication device. Because a receiver implemented in a communications transceiver may be called upon to amplify and process a weak receive signal, receiver noise may be a particular source of concern. Receiver noise can occur in the form of front-end noise, for example, or as noise produced by the receiver matching network. In addition, flicker noise may be produced by a mixer circuit utilized to down-convert a receive signal.
In a conventional receiver, the problem of flicker noise may be largely resolved through placement of a blocking capacitor, which is typically selected to be as large as possible for maximum noise suppression, between the transconductance amplifier situated at the input of the receiver, and the mixer. Unfortunately the presence of a large blocking capacitor may reduce the overall front-end gain of the receiver, which is an undesirable result when weak receive signals are being processed.
The problems presented by the front-end noise and matching network noise may be even more intractable, because techniques directed to achieving noise matching between the receiver front-end and the matching network for the purpose of reducing their combined noise are often at odds with achieving impedance matching between the matching network and receiver front-end. As a result, conventional receiver designs must carefully balance the competing interests of noise matching and impedance matching when implementing a receiver, with advantageous improvements in one operating parameter typically resulting in undesirable deterioration of the other.
Thus, there is a need to overcome the drawbacks and deficiencies in the art by providing a receiver designed to enable concurrent impedance and noise matching with its matching network. In addition, it is desirable that the receiver avoid the reduction in front-end gain associated with flicker noise suppression in conventional receivers.